The present invention relates to an industrial vacuum loading device and, more particularly, to a mobile vacuum loading apparatus particularly adapted to be mounted on a conventional pick-up truck.
Industrial vacuum loading devices are well known in the art and are utilized in a wide variety of applications where large amounts of particulates, as well as much larger and heavier scrap and waste materials of many types, must be rapidly picked up and collected for disposal. An industrial vacuum loading apparatus utilizes a high volume induced air flow through a filter chamber to carry particulates and other materials into the chamber, where they are separated and filtered out of the airstream, collected by gravity in a lower collecting bin, and eventually removed for disposal. The clean filtered air drawn through the system by an induced draft blower is discharged to the atmosphere.
Large stationary and truck mounted vacuum loaders typically utilize several stages of separation for the particulates and other materials collected. Thus, the incoming particulate-laden air may be initially directed into a settling chamber where the heavy materials and large particulates drop out into a lower collecting bin. Some units then direct the particulate-laden air into a cyclone-type separator to remove an additional amount of the smaller particulates. The main filtering elements for these units typically comprise a bag house utilizing a series of cloth-like filter bags mounted on an open supporting framework and through which the air flow passes with the particulates being filtered out by the filter bags. The air exiting the bag house filters may be finally filtered by passing it through one or more filter cartridges, typically utilizing a conventional pleated filter media. The particulates and other materials which are collected by gravity in the lower collecting bins are discharged through lower hopper openings or by tilting the unit and dumping the particulates therefrom. The filter bags and filter cartridges are usually cleaned by directing a reverse backflushing jet of compressed air into the bag or cartridge outlet to dislodge the particulate material clinging to the upstream face of the filter media. The backflushed particulates typically fall by gravity to the bottom of the filter chamber and may be unloaded therefrom in a manner similar to the unloading of the main collecting bin. However, some industrial units are constructed with the filter housings located above the main collecting bin with discharge openings that can be selectively opened to allow the back flushed particulates to be discharged directly into the main collecting bin. This requires the flow of particulate-laden air to be temporarily halted or the flow through the filter chamber to be temporarily bypassed.
Because large industrial units can be sized to provide excess filter capacity, temporary shutoff or bypass of the particulate-laden air through a portion of the filter system to accommodate back flushing is generally not a problem. In addition, power requirements and size and space limitations are not critical problems in large industrial units, either stationary or mounted on heavy duty trucks. Thus, these units can be sized to provide large volumes of air flow, multiple separation and filtering stages, greatly excess filter capacity to allow on-stream cleaning, and large air compressors to provide the compressed air for back flush cleaning.
In attempting to downsize a stationary vacuum loader or a large mobile vacuum loader mounted on a heavy duty truck, the power requirements and the size and weight limitations present acute problems. The large volume filtering chamber needed to accommodate a conventional bag house filter is simply not available, for example, in the space confines provided by the bed of a conventional pick-up truck. Likewise, the space required for multiple separation and filtering stages is not available. Nevertheless, a real need exists for a smaller, less costly, and more mobile vacuum loader apparatus which can be mounted directly on a commercially available pick-up truck chassis.
As indicated, it is known in the art to utilize a filter cartridge having a pleated filter media for one filtering stage in a vacuum loading apparatus. It is also known to backflush such filter cartridges with a jet of compressed air injected into the cylindrical interior upstream side of the unit. However, in mobile vacuum loading apparatus, pleated filter cartridges have been relegated to secondary filtering stages where the particulate loadings are low and space is available to provide a high filtering capacity. In large stationary units, space is also generally not a problem and, therefore, filter cartridges providing an excess of filter capacity can be provided such that one or more filter cartridges may be periodically taken off-line for backflushing without interferring with the total flow of air through the system. Thus, the downsizing of heavy duty truck mounted or stationary vacuum loaders to adapt them to be used on smaller conventional pick-up truck bodies presents a number of problems which preclude straightforward reduction in size.